leukemias

Leukemias are cancers of the blood and bone marrow characterized by the unchecked growth of abnormal white blood cells. They originate from hematopoietic stem cells and disrupt normal blood formation.

Classification distinguishes acute versus chronic forms and lymphoid versus myeloid lineages. The four major subtypes are acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), and chronic myeloid leukemia (CML).

Signs and symptoms include fatigue, infections, fever, anemia-related pallor, easy bruising or bleeding, night sweats, weight loss, and bone pain. CNS symptoms can occur with some subtypes.

Risk factors include genetic syndromes (eg, Down syndrome), prior chemotherapy or radiation, exposure to benzene, smoking, and family history. Most cases arise from acquired mutations in hematopoietic cells.

Diagnosis relies on blood tests and marrow analysis. A complete blood count, peripheral smear, bone marrow biopsy with cytogenetics and molecular testing, and flow cytometry are commonly used, aided by imaging as needed.

Treatment varies by type and risk. Common approaches include chemotherapy, targeted therapies (eg, tyrosine kinase inhibitors for CML), immunotherapy such as CAR-T cells, monoclonal antibodies, radiation in limited cases, and stem cell transplantation. Supportive care is essential.

Prognosis depends on subtype, age, cytogenetics, and response to therapy. Children with ALL often have favorable outcomes, while AML outcomes are more variable in adults. CML typically has a good prognosis with targeted therapy.

Epidemiology and research: Leukemias occur across ages, with ALL most common in children and AML more common in adults. Ongoing research focuses on precision medicine, minimal residual disease, and novel immunotherapies.